Signaling system



g- 6, 1929- E. F. w. ALEXANDERSON 1,722,998

SIGNALING SYSTEM Filed May 11, 1923 in a ) Inventor;

Ernst. F \M Alexan derson' a M w His Ant OPTWeH.

Patented Aug. 6, 1929.

UNITED STATES PATENT OFFICE.

ERNS'I F. W. ALEXANDERSON, 9F SCHENEGTADY, NEFN YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEN YORK.

SIGNALING Application filed May 11,

My present invention relates to signaling systems, and more particularly to a system for receiving and detecting high frequency continuous wave signals.

One of the objects of my invention is to provide a receiving system in which the disturbing effects of stray current or currents from interfering stations will be largely eliminated.

Preferably my invention may be carried out by means of apparatus of the magnetron type such as described and claimed in my Patent 1,549,737, issued August 18, 1925, and my invention is, in its essential details, an improvement over the invention described in that application.

The novel features which I believe to be characteristic ofmy invention are set forthwith particularity in the appended claims. My invention itself, however, will be best understood by reference to the following description taken in connection with the accompanying drawing in which I have indicated diagrammatically one way in which my invention may be carried into effect.

I have indicated in the drawing a receiving system for receiving and detecting continuous wave telegraphic signals received upon the antenna 1. Signals received upon the antenna 1 are impressed by means of the coupling transformer 2 upon a circuit arrangement comprising two asymmetric current paths formed by electron discharge de vices 3 and 4 of the magnetron type. Each of these magnetrons has the usual filamentary cathode 5 and a cylindrical anode 6. Opposite terminals of the secondary 7 of transformer 2 are connected to the anodes 6 through the primaries 8 of transformers 9. The middle point of secondary 7 is connected to the cathodes of the magnetrons through a resistance 10 having a large value in comparison with the resistances of the paths as for example a value of the order of magnitude of a megohm or more and a direct current source 11 and potentiometer 12. Current for heating the cathodes 5 is supplied by a direct current source 13 which is connected in series with the two cathodes through a regulating resistance 14. The magnetic field necessary for the operation of the magnetrons is furnished by magnetizing coils 15 which are supplied with alternating current from source 16 through condensers 17 A polarizing magnetic field is SYSTEM.

1923. Serial N0. 638,363.

produced by means of current from source 13 which is supplied to coils 15 through a regulating resistance 18. The secondaries of transformers 9 are connected in series with each other and in series with an indicating instrument illustrated diagrammatically as telephone receiver 19.

In the operation of the system described, the resistance 10 and the potential applied to the circuit from the source 11 are so adjusted that the current which will flow through the two magnetrons in parallel will be of the same order of magnitude as the maximum signal current which may be produced. The source 16 should preferably be of a frequency slightly different from that of'the signals to be received. The currents supplied to the magnetizing coils 15 from the sources 13 and 16 should be so proportioned that during the half cycle of the current supplied from source 16 that current flows in the same direction as the current from source 13 the magnetizing field will be strong enough to prevent current from flowing through the maguetrons, while during the other half cycle the magnetic field will be reduced in strength sufficiently to permit current to flow through the magnetrons.

\Vhen no signal is being received the current variations produced in the magnetrons by the variations in the magnetic fields will produce no effect in the telephone receivers 19. lVhen a signal is impressed upon the secondary 7, however, one terminal of secondary 7 will become more positive and the current. flowing through the primary 8 of the corresponding transformer 9 will increase while at the same time the other terminal of secondary 7 will become more negative and the current flowing through the primary 8 of the corresponding transformer 9 will decrease. As a result a current will flow through the telephone receivers 19 which will continue as long as current flows through the magnetrons but will be interrupted as soon as the magnetron current is interrupted. The current in the telephone receivers will be of the same nature as the current produced in the apparatus described in Patent 1,549,737, that is, it will produce in the telephone receivers an effect similar to that which would be produced by an alternating current of a frequency equal to the difference in frequency between the source 16 and the signaling frequency.

The value of the current which can flow through the two magnetrons, in parallel is substantially fixed by the limiting resistance 10. The maximum effect which can be produced in the receiving circuit by potentials impressed upon the secondary T will be a reduction of current in the primary 8 of one of the transformers to substantially Zero and an increase in the current through the primary of the other transformer to substantially twice its normal value. If the system is so adjusted that this maximum change will be brought about by the normal signaling potential any disturbing or stray potentials of greater magnitude will have substantially no effect in the receiving sys tem.

Detection of the received signals is accomplished in the system which I have described by what may be termed the chopping action without any rectification as the terminals of the detector circuit are connected to the anodes of he magnetrons and the resistance 10 is of such high value that it is in effect an open circuit for both the high frequency and the audio frequency current. By avoiding any detection by rectification the receiving system is rendered less sensi-' tive to interference.

While I have shown and described only one modification of my invention it is apparent that many modifications in the apparatus used as well as in the circuit connections may be made without departing from the scope of my invention as set forth in the appended claims.

hat I claim as new and desire to secure by Letters Patent of the United States, is:

l. The combination in a signal receiving system of a circuit arrangement which includes a pair of asymmetric current paths through which current may be carried by negative electrons, means for producing a llow of current through said paths in parallel, means for impressing signaling poteniials upon said circuit arrangement to produce equal. and opposite simultaneous current \ariations in the two paths, and means i". producing magnetic fields which act direci'ly on the electrons in said paths and periodically vary the current flow therethrough.

2. The combination in a signal receiving system of a circuit arrangement which includes a pair of asymmetric current paths through which current may be carried by negative electrons, means for producing a flow of current through said paths in parallel, means for impressing signaling potentials upon said circuit arrangement to produce equal and opposite simultaneous current variations in the two paths and means for producing magnetic fields which act directly on the electrons in said paths and periodically vary the current flow therethrough at a frequency slightly different from the signaling frequency.

3. The combination in a signal receiving system of a circuit arrangement which includes a pair of asymmetric current paths through which current mav be carried by negative electrons, means for producing a flow of current through said paths in parallel, means for impressing signaling potentials upon said circuit arrangement to produce equal and opposite simultaneous current variations in the two paths, means for limiting the current variations which may be thus produced to a predetermined value, and means for producing magnetic fields which act directly on the electrons in said paths and periodically vary the current flow therethrough.

4. The combination in a signal receiving system of a circuit arrangement which includes a pair of asymmetric current paths through which current may be carried by negative electrons, a source of current for producing a flow of current through said paths in parallel, a current limiting resist-- ance of large value in comparison with the resistance of said paths in series with said source, means for impressing signaling potentials upon said circuit arrangement to produce equal and opposite simultaneous current variations in the two paths and means for producing magnetic fields which act directly on the electrons in said paths and periodically vary the current flow therethrough.

5. The combination in a signal receiving system of a circuit arrangement which includes a pair of asymmetric current paths through which current may be carried by negative electrons, a source of current for producing a flow of current through said paths in parallel, a current limiting resist ance of large value in comparison with the resistance of said paths in series with said source, means for impressing signaling potentials upon said circuit arrangement to produce equal and opposite simultaneous current variations in the two paths and means for producing magnetic fields which act directly on the electrons in said paths and periodically vary the current flow therethrough at a frequency slightly different from the signaling frequency.

6. The combination in a signal receiving system of a pair of asymmetric current paths sponding terminals of said current paths,

means for impressing signaling potentials upon said winding, and means for producing magnetic fields which act directly on the electrons in said paths and periodically vary the current flow therethrough.

7. The combination in a signal receiving system of a pair of symmetric current paths through which current may be carried by negative electrons, said paths being connected in parallel to a source of current, a winding having its opposite terminals connected to corresponding terminals of said paths and having an intermediate point connected to one terminal of said source of current through a current limiting resistance of large value in comparison with the norma'l resistance of the two paths, the other terminal of said source of current being connected to the other corresponding terminals of said current paths, means for impressing signaling potentials upon said Winding, and means for producing magnetic fields which act directly on the electrons in said paths and periodically vary the current flow therethrough.

8. The combination in a signal receiving system of a circuit arrangement which includes a pair of asymmetric current paths through which current may be carried by negative electrons, means for producing a flow of current through said paths in parallel, means for impressing signaling potentials upon said circuit arrangement to produce equal and opposite simultaneous current variations in the two paths, means for impressing upon an indicating device eurrent variations produced by signaling potentials in said paths, and means for producing magnetic fields which act directly on the electrons in said paths and periodically vary the current flow therethrough.

9. The combination in a signal receiving system of a pair of asymmetric current paths through which current may be carried by negative electrons, said paths being connected in parallel to a source of current, an indicating device, a winding having its opposite terminals connected to corresponding terminals of said paths through the primaries of a pair of transformers, the secondaries of which are connected to said indieating device, and having an intermediate point connected to one terminal of said source of current, the other terminal of said source of current being connected to the other corresponding terminals of said current paths, means for impressing signaling potentials upon said Winding, and means for producing magnetic fields which act directly on the electrons in said paths and periodically vary the current fiow therethrough.

10. The combination in a signal receiving system of a pair of asymmetric current paths through which current may be carried by negative electrons, said paths being connected in parallel to a source of current, an indicating device, a winding having its opposite terminals connected to corresponding terminals of said paths through the primaries of a pair of transformers, the secondaries of which are connected to said indicating device and having an intermediate point connected to one termin-a1 of said source of current through a current limiting resistance of large value in comparison with the normal resistance of the two paths, the other terminal of said source of current being connected to the other corresponding terminals of said cur rent paths, means for impressing signaling potentials upon said winding, and means for producing magnetic fields which act directly on the electrons in said paths and periodically vary the current flow therethrough.

11. The combination in a signal receiving system of a pair of asymmetric current paths through each of which current may be conducted by means of negative electrons flowing from an electron emitting cathode to a cooperating anode, a source of current having its negative terminal connected to the cathode terminals of said paths and its positive terminal connected to the anode terminals, means for simultaneously impressing upon the circuit connections of the two paths signaling potentials of opposite polarity, and means for producing magnetic fields which act directly on the electrons in said paths and periodically vary the current flow therethrough.

12. The combination in a signal receiving system of a pair of asymmetric current paths through each of which current may be conducted by means of negative electrons flowing from an electron emitting cathode to a cooperating anode, a source of current having its negative terminal connected to the cathode terminals of said paths, and its positive terminal connected to the anode terminals, a current limiting resistance of large value in comparison with the resistance of said paths included in the circuit connections between said source and said paths, and means for producing magnetic fields which act directly on the electrons in said paths, and periodically vary the current flow therethrough.

13. The combination in a signal receiving system of a pair of asymmetric current paths through each of which current may be conducted by means of negative electrons flowing from an electron emitting cathode to a cooperating anode, a source of current having its negative terminal connected to the cathode terminals of said paths, and its positive terminal connected to the anode terminals, means for simultaneously impressing upon the circuit connections of the polarity, an indicating device, means for impressing upon said indicating device current variations produced in said paths by impressed signaling potentials, and means for producing magnetic fields which act directly on the electrons in said paths and periodically vary the current flow therethrough.

ll. The combination in a signal receiving system of a pair of asymmetric current paths through each of which current may be conducted by means of negative electrons flowing from an electron emitting cathode to a cooperating anode, a source of current having its negative terminal connected to the cathode terminals of said paths and its positive terminal connected to the anode terminals, a current limiting resistance of large value in comparison with the resistance of said paths included in the circuit connections between said source and said paths,

means for simultaneously impressing upon the circuit connections of the two paths sig- In witness whereof, I have hereunto set so my hand this 10th day of May, 1923.

ERNST F. W. ALEXANDERSON.

CERTIFICATE OF CORRECTION.

Patent No. 1,722,998. Granted August 6, 1929, to

ERNST F. W. ALEXANDERSON.

It is hereby certified that errer ago eears in the printed specification of the above numbered patent requiring correetion as follows: Page 3, line 7, claim 7 for the word "symmetric" read "asymmetric"; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the ease in the Patent Oiiioe.

Signed and sealed this llith day of September, A. D. 1929.

M. J. Moore, (Seal) Acting Commissioner of Patents. 

